Major Continental Divides of North America
A continental divide separates major streams that ultimately flow in divergent paths and will not join each other before they enter an ocean or sea. Also, a continental divide separates surface waters that ultimately flow to different oceans, different seas, or different coastlines on different sides of a continent. From these criteria, the North American continent has at least four distinct continental divides that separate drainages of the Pacific Ocean, Arctic Ocean, Hudson Bay, Gulf of St. Lawrence, Gulf of Mexico, and Atlantic Seaboard (Fig. 3). Three of these divides have pre-existing formal names: the Great Divide, the Northern Divide, and the Eastern Divide. The fourth divide is herein referred to as the St. Lawrence Seaway Divide. These divides are described below.
See Fig. 3.
The Northern Divide
An examination of the major drainage basins, or watersheds, of the North American continent shows that the headwaters of several major drainage basins bear no relation to the Great Divide. For example, the headwaters of the Mississippi River system, the Ohio River system, the Nelson/Red-River-of-the-North system, and Great Lakes system (or St. Lawrence Seaway) originate deep in the interior of the North American continent and far from the Rocky Mountains and the Great Divide. Nevertheless, these basins drain into different oceans or seas on different sides of the continent.
The drainage divide, which separates drainages to the Hudson Bay and Arctic Ocean from all other drainages in North America, is known as the Northern Divide. In northern Minnesota, the Northern Divide is commonly known as the Laurentian Divide. The Northern Divide shares the same path as the Great Divide from Seward Peninsula to Triple Divide Peak, Montana. From Triple Divide Peak, the Northern Divide trends to the east through Montana, Alberta, Saskatchewan, North Dakota, South Dakota, and Minnesota. The Laurentian Divide in Minnesota follows an especially prominent ridge that runs for 120 miles from just east of Grand Rapids to Hoyt Lake. The Chippewa or Ojebwe Indians referred to this stretch of the Laurentian Divide as the sleeping giant, or Mesabi. The Mesabi Range is well known for the high-grade iron ore that was mined for decades. From northern Minnesota, the Northern Divide continues north and east across parts of Ontario and Quebec. It eventually demarcates the boundary between Quebec and Newfoundland and Labrador. It terminates at the coastline marking the boundary between the Labrador Sea and Hudson Bay.
North Dakotans will readily recognize the approximate trace of the Northern Divide across the state by examining the state's major drainages. Streams in the west, southwest, and south-central parts of North Dakota, such as the James, Cannonball, Cedar, Heart, Knife, and Little Missouri rivers, flow to the Missouri River, which in turn joins the Mississippi River and eventually flows to the Gulf of Mexico. In contrast, streams of the northwest, north, and eastern parts of the state, such as the Souris River, the Red River of the North, and all their tributaries, including the Sheyenne, Goose, Maple, Pembina, Tongue, and Turtle rivers, flow to Hudson Bay (Fig. 4). In the southern part of the state, the continental divide runs between the James and the Sheyenne valleys from the border with South Dakota northward toward Harvey. South of Harvey, the divide angles westward and roughly follows a crest in the Missouri Coteau that is slightly west and south of the Missouri Escarpment.
The Northern Divide is not just of geographic and hydrologic importance, but it has political significance too. When the Louisiana Purchase was added to the United States in 1803, the Northern Divide served as the boundary between the territory of the United States and Great Britain (Canada). The present-day boundary between the United States and Canada was not established until 1818, when the Treaty of Ghent set the international boundary at 49º N latitude.
See Fig. 4.
The Northern Divide still has important political ramifications, because water in North Dakota drains into Canada. For example, Manitoba is citing international water laws, treaties, and compacts in its concerns over the Northwest Water Pipeline, which diverts water from the Missouri River to Minot, the proposed Garrison Diversion, which would divert Missouri River water to all of eastern North Dakota, and the planned Devils Lake outlet, which would transfer water from a closed basin to the Sheyenne/Red River system.
References:
"Continental Divides in North Dakota and North America". NationalAtlas.gov. Archived from the original on 2008-05-13. Retrieved 2010-12-01.
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- What is the elevation at the Historical marker.
2. Water flows which direction standing on the Northeast side of the Marker?
3. Water flows which direction standing on the Southwest side of the Marker?
4. What is another name for the Northern Divide which is used in Minnesota?
5. What other significance does the Northern Divide have besides hydrologic ?